Gastric Dilation and Intestinal Obstruction – Rabbit

Introduction: gastric dilation and gut stasis

Gastric stasis must be differentiated from gastric dilation which is usually associated with intestinal obstruction. Gastric dilation develops rapidly, suddenly and unexpectedly, whereas gut stasis develops slowly and insidiously, usually followed by a painful or stressful episode. Note that a moving foreign body could mimic gut stasis except that the stomach is not impacted (stomach may or may not be impacted).

For more information, see:

Harcourt Brown F M (2007), Gastric dilation and intestinal obstruction in 76 rabbits. Veterinary Record, 161, 409 – 414, and
Harcourt Brown T R (2007) Management of Acute Gastric Dilation in Rabbits. Journal of Exotic Pet Medicine, 16, (3) 168 – 174

Pathophysiology

(Pathological) obstruction of small intestine accompanied by (physiological) continuous production of saliva which leads to:

Accumulation of fluid in stomach and small intestine cranial to obstruction
Fermentation => gas production
Painful gastrointestinal dilation
Reduced gut motility
Secondary ileus.
Sequestration of fluid => electrolyte and acid-base imbalances and hypovolaemia (and the necessity of fluid therapy.
Passage of blockage to hind gut
- note dilation of gut proximal to obstruction
Non-passage of the blockage leads to devitalisation and necrosis of intestine

Clinical Signs of Gastric Dilation

Anorexia
Depression
Moribund/unresponsive
Death (due to peritonitis or shock)
Distended stomach palpable in left epigastric area caudomedial to left last rib and confirmed radiographically
Abdominal pain or flaccidity

Causes of intestinal obstruction

Compressed hair
Intestinal neoplasia
- Lymphoma
Foodstuff
Post-spay adhesions
Post-castration strangulated hernia
Foreign fibre
Tapeworm cysts
Diverticulosis

Pellets of compressed hair

They are acquired by:

grooming/moulting
Ingestion of matted hair
Ingestion of hair in caecotrophs
Predisposed by low-fibre diets

Sites and causes of obstruction

Pylorus (Deeb 2000; Jenkins 2003)
Proximal duodenum
- foreign bodies
- mid-small intestine
- foreign bodies
- neoplasia
- strangulated hernia
- diverticulosis
Ileocaecocolic junction
- foreign bodies
- neoplasia
Large intestine
- neoplasia
- carpet fibre at fusus coli
- postspay adhesions
- tapeworm cysts along attachment with small intestine

NB: Severity of prognosis is directly proportional to closeness of site of obstruction to pylorus.

Case assessment


Clinical signs	Radiographic signs	Conclusion
Unresponsive; collapsed; hypothermic; abdominal pain; +/- gastric dilation	Gas in stomach and intestine; free gas in peritoneal cavity	Ruptured gut; explorotomy; euthanasia
Unresponsive; abdominal pain; gastric dilation palpable	Gas/fluid in stomach; minimal gas in intestine	Cranial sm int obstruction; gastric decompression and surgery; euthanasia
Unresponsive; abdominal pain; gastric dilation palpable	Gas/fluid in stomach; much gas in small intestine	Caudal sm int obstruction; repeat rads (30-60 mins) or perform gastric decompression
Depressed; not collapsed; palpably enlarged stomach	Gas in caecum	Foreign body has passed through; medical treatment

Performing surgery only to find that the obstruction has moved is preferable to performing a post-mortem examination on a rabbit that required surgical intervention. (Harcourt Brown T R (2007), Journal of Exotic Pet Medicine. 16, (3) 168-174)

Procedure with a case of gastric dilation

Radiograph under opiate analgesia - fentanyl/fluanisone ((Hypnorm; Janssen-Cilag) SC once only or buprenorphine (Vetergesic; Alstoe) plus meloxicam (Metacam; Boehringer Ingelheim) or carprofen (Rimadyl; Pfizer). Prepare orthogonal radiographs - lateral and dorso-ventral with legs extended or ventro-dorsal views. Observe the dilation of the stomach and the presence and distribution of fluid (liquid and gas) in the gastrointestinal tract to identify location of obstruction. Note the degree of contact of the dilated stomach with the ventral abdominal wall. Assess the amount of gas in the small intestine and look for gas in the large intestine. If no gas in hindgut and stomach severely dilated it may be best to go for euthanasia. Free gas in peritoneum indicates rupture of the gastrointestinal tract and justifies euthanasia. A search for other pathology may indicate other problems like bladder stones, spinal arthritis etc and may also indicate euthanasia.

Pit-falls of radiography: Caecum and large intestine generally do not have large amounts of gas in normal rabbits BUT caecum and large intestine generally do not have no gas in obstructed rabbits Caecum and large intestine with gas and dilated stomach seen in cases carrying a better prognosis.

Search for peritoneal gas in rabbits with severe depression If found, this is an indication of rupture of the intestine and indicates euthanasia. Remember euthanasia always an option

Serial radiographs (every 30 – 90 minutes) looking for gas in hindgut. If gas in hind gut this indicates that the obstruction is moving - administer NSAIDs (carprofen or meloxicam) if not already administered (see above) - followed by prokinetics if still anorectic after 2-3 hours.

Fluid accumulation in stomach leads to deficit in intra- and extra-cellular compartments. Parenteral fluids required. Give Hartmann’s/kg /hr IV.

Exploratory surgery may be attempted. Decision of whether to embark on surgery or conservative treatment depends on the time of presentation and on financial considerations:

Day => conservative treatment
Night => surgery more likely

Surgical Procedure

Insert stomach tube to decompress: if it blocks, remove, flush and replace
- Procedure of gastric decompression
  - +/- sedation
  - mouth to last rib
  - gentle gastric massage
  - patience
  - minimal suction
  - intermittent retropulsion
  - if tube is placed inadvertently endotracheally there will be
a change in breathing pattern
the presence of breath sounds at the free end of the tube
intraluminal condensation
Gastric rupture => euthanasia
Intestinal rupture => euthanasia
Intestinal neoplasm => euthanasia
Intestinal FB milked through ileocaecocolic junction into the hind gut or perform an enterotomy.
Note small omentum so omentalisation may not be possible
Postoperatively give antibiotics, prokinetics, food (force fed with Oxbow Critical Care Formula and baby cereal)

Practical approach to exploratory laparotomy in rabbits with intestinal obstruction

Opiate premedication, oxygenation, gastric and tracheal intubation and isoflurane maintenance.
Incision midline, sternum to umbilicus
Inspect retroperitoneum for fluid/ingesta
Palpate stomach and descending duodenum
Palpate ascending duodenum (under caecum)
Palpate jejunum cranially and caudally
Look for flattened intestine caudal to obstruction
Examine site of obstruction for contributive or subsequent pathology: cytology/biopsy?
Milk obstruction to hindgut or stomach
Gastrotomy/enterotomy/ectomy???
Closure with Vicryl (not catgut)

Complications of rabbit intestinal surgery

Insufficient omentum for omentalisation
Intestine small and thin-walled
Food cannot be withheld during post-operative period
- danger of hepatic lipidosis

Postoperative care

Warmth, quiet
Fluid therapy
Analgesia
Antibiotics
Prokinetics
Food (grass, dandelions)
Gavage with Oxbow CCF and Baby cereal

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References

Deeb, B. (2000) Digestive System and Disorders in Manual of Rabbit Medicine and Surgery, ed. Paul Flecknell pub BSAVA Cheltenham Glos Pages 39 - 46
Harcourt Brown, F. M. (2007) Gastric dilation and intestinal obstruction in 76 rabbits. Veterinary Record, 161, 409 – 414
Harcourt Brown, T. R. (2007) Management of Acute Gastric Dilation in Rabbits. Journal of Exotic Pet Medicine, 16, (3) 168 – 174